The present disclosure relates to fluid flow in extravascular systems used to provide infusion or other therapy to patients. Infusion therapy is one of the most common health care procedures. Hospitalized and home care patients receive fluids, pharmaceuticals, and blood products via a vascular access device inserted into the vascular system. Infusion therapy may be used to treat an infection, provide anesthesia or analgesia, provide nutritional support, treat cancerous growths, maintain blood pressure and heart rhythm, or many other clinically significant uses.
Infusion therapy is facilitated by vascular access devices located outside the vascular system of a patient. An extravascular system includes at least one vascular access device and/or other medical device that may access a patient's peripheral or central vasculature, either directly or indirectly. Vascular access devices include closed access devices, such as the BD Q-SYTETM closed Luer access device of Becton, Dickinson and Company; syringes; split access devices; catheters; and intravenous (IV) fluid chambers. An extravascular system may access a patient's vascular system for a short term (days), a moderate term (weeks), or a long term (months to years), and may be used for continuous infusion therapy or for intermittent therapy.
A common vascular access device is a plastic catheter that is inserted into a patient's vein. The catheter length may vary from a few centimeters for peripheral access to many centimeters for central access. The catheter may be inserted transcutaneously or may be surgically implanted beneath the patient's skin. The catheter, or any other vascular access device attached thereto, may have a single lumen or multiple lumens for infusion of many fluids simultaneously.
Although several techniques for placing such catheters are practiced in the art, many generally include the step of inserting at least a portion of the needle into the target vessel and then sliding the catheter over the needle into place. The medical worker attempts to verify proper placement of the catheter within the blood vessel. Catheter and introducer needle assemblies have been provided that include means for verifying proper placement of the catheter in a blood vessel such as a flashback chamber in the catheter hub or a notch in the introducer needle.
Once placement of the needle has been confirmed by the observation of flash, the user may temporarily occlude flow in the blood vessel at the catheter tip, remove the needle, leaving the catheter in place, and attach a device to the catheter for fluid removal, input, or to seal the catheter. This process has been somewhat difficult in practice since many placement sites simply do not allow easy occlusion of the target vessel. Additionally, even when such occlusion is achieved, it may be imperfect, thus resulting in blood leaking from the catheter, endangering the medical personnel employing it.
Catheter and introducer needle assemblies have thus been provided in the art that provide a variety of seals or valve mechanisms for preventing outflow of fluid during and following removal of the introducer needle. These structures are generally elastomeric plates designed to closely conform to the shape of a needle during storage and use to prevent leaking, then to seal upon removal of the needle. In an ideal vascular access device, the septum would continuously seal the patient's vascular system, which may include external vascular equipment intentionally coupled to the patient's internal vascular system by a medical practitioner, from the external environment.
Complications associated with infusion therapy include significant morbidity and even mortality. Such complications may be caused by regions of stagnant fluid flow within the vascular access device or nearby areas of the extravascular system. These are regions in which the flow of fluid is limited or non-existent due to the conformation of the septum or valve mechanism in the extravascular system or the fluid dynamics within that area of the extravascular system. Blood, air bubbles or infused medications may become trapped within these regions of stagnant flow as a result of the limited or non-existent fluid flow. When blood is trapped within the extravascular system bacteria can breed which can lead to infections. When a different medication is infused into the extravascular system, or the extravascular system is exposed to physical trauma, the extravascular system's fluid flow may become altered, releasing trapped air bubbles or residual medications back into the active fluid path of the extravascular system. This release of air bubbles and residual medication into the active fluid path extravascular system may result in significant complications.
Released air bubbles may block fluid flow through the extravascular system and prevent its proper functioning. More seriously, released air bubbles may enter the vascular system of the patient and block blood flow, causing tissue damage and even stroke. In addition, residual medications may interact with presently infused medications to cause precipitates within the extravascular system and prevent its proper functioning. Furthermore, residual medications may enter the vascular system of the patient and cause unintended and/or undesired effects.
Therefore the need exists for valve mechanisms in vascular access devices that eliminate, prevent, or limit regions of stagnant flow vascular access devices and extravascular systems to provide better flush properties.